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-rw-r--r--lib/Sema/SemaExpr.cpp12
-rw-r--r--test/Sema/expr-comma-c89.c18
-rw-r--r--test/Sema/expr-comma.c12
3 files changed, 34 insertions, 8 deletions
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 8a4752ab1e..9ffca0870c 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -58,8 +58,16 @@ void Sema::DefaultFunctionArrayConversion(Expr *&E) {
}
if (Ty->isFunctionType())
ImpCastExprToType(E, Context.getPointerType(Ty));
- else if (Ty->isArrayType())
- ImpCastExprToType(E, Context.getArrayDecayedType(Ty));
+ else if (Ty->isArrayType()) {
+ // In C90 mode, arrays only promote to pointers if the array expression is
+ // an lvalue. The relevant legalese is C90 6.2.2.1p3: "an lvalue that has
+ // type 'array of type' is converted to an expression that has type 'pointer
+ // to type'...". In C99 this was changed to: C99 6.3.2.1p3: "an expression
+ // that has type 'array of type' ...". The relevant change is "an lvalue"
+ // (C90) to "an expression" (C99).
+ if (getLangOptions().C99 || E->isLvalue() == Expr::LV_Valid)
+ ImpCastExprToType(E, Context.getArrayDecayedType(Ty));
+ }
}
/// UsualUnaryConversions - Performs various conversions that are common to most
diff --git a/test/Sema/expr-comma-c89.c b/test/Sema/expr-comma-c89.c
new file mode 100644
index 0000000000..4949ee3a83
--- /dev/null
+++ b/test/Sema/expr-comma-c89.c
@@ -0,0 +1,18 @@
+// RUN: clang %s -fsyntax-only -verify -std=c99
+// rdar://6095180
+
+#include <assert.h>
+struct s { char c[17]; };
+extern struct s foo(void);
+
+struct s a, b, c;
+
+int A[sizeof((foo().c)) == 17 ? 1 : -1];
+int B[sizeof((a.c)) == 17 ? 1 : -1];
+
+
+// comma does array/function promotion in c99.
+int X[sizeof(0, (foo().c)) == sizeof(char*) ? 1 : -1];
+int Y[sizeof(0, (a,b).c) == sizeof(char*) ? 1 : -1];
+int Z[sizeof(0, (a=b).c) == sizeof(char*) ? 1 : -1];
+
diff --git a/test/Sema/expr-comma.c b/test/Sema/expr-comma.c
index 4949ee3a83..849e8d5ae8 100644
--- a/test/Sema/expr-comma.c
+++ b/test/Sema/expr-comma.c
@@ -1,4 +1,4 @@
-// RUN: clang %s -fsyntax-only -verify -std=c99
+// RUN: clang %s -fsyntax-only -verify -std=c89
// rdar://6095180
#include <assert.h>
@@ -11,8 +11,8 @@ int A[sizeof((foo().c)) == 17 ? 1 : -1];
int B[sizeof((a.c)) == 17 ? 1 : -1];
-// comma does array/function promotion in c99.
-int X[sizeof(0, (foo().c)) == sizeof(char*) ? 1 : -1];
-int Y[sizeof(0, (a,b).c) == sizeof(char*) ? 1 : -1];
-int Z[sizeof(0, (a=b).c) == sizeof(char*) ? 1 : -1];
-
+// comma does not promote array/function in c90 unless they are lvalues.
+int W[sizeof(0, a.c) == sizeof(char*) ? 1 : -1];
+int X[sizeof(0, (foo().c)) == 17 ? 1 : -1];
+int Y[sizeof(0, (a,b).c) == 17 ? 1 : -1];
+int Z[sizeof(0, (a=b).c) == 17 ? 1 : -1];